If you want the minis you should get them from the States. If you want to buy it there, just ask a taxi driver to take you to the liquor store when you get there. I'm pretty sure the smallest they sell is a half pint. Also Bacardi is Puerto Rican - If you want a Bahamian Rum - they have Ron Ricardo, John Watling's, and Old Nassau

I don't know about the cakes but I see them for sale at the straw market, downtown shops and the airport